CCNP / BSCI Test Tutorial: Route Summarization As well as OSPF Null Interface
CCNP Test achievement, specifically within the BSCI Test, demands you comprehend the details of route summarization. This talent don't just involves that you've got a convenience degree with binary conversions, but you have to understand how and exactly where to use route summarization with Each individual individual protocol.
You also have to understand the “Unintended effects” of route summarization. With OSPF, there will in fact be an extra interface established at the point of summarization, and this catches plenty of CCNP candidates unexpectedly. Permit’s Have a look at the null0 interface And the way it pertains to OSPF summarization.
On R1, the following networks are redistributed into OSPF, then summarized.
interface Loopback16
ip handle 16.16.16.sixteen 255.0.0.0
interface Loopback17
ip deal with seventeen.seventeen.seventeen.17 255.0.0.0
interface Loopback18
ip tackle 18.18.18.18 255.0.0.0
interface Loopback19
ip tackle 19.19.19.19 255.0.0.0
R1(config)#router ospf one
R1(config-router)#redistribute related subnets
R1(config-router)#summary-deal with 16.0.0.0 252.0.0.0
The summary address seems on R2, a downstream router.
R2#present ip route ospf
O E2 16.0.0.0/6 [110/twenty] through 172.12.123.1, 00:00:05, Serial0
Let’s go back to 먹튀검증 R1 and evaluate its OSPF table.
R1#present ip route ospf
O 16.0.0.0/six can be a summary, 00:01:51, Null0
Wherever did the null0 interface come from, and why can it be there? Packets sent for the null interface are dropped, and In cases like this, that’s a fantastic matter.
Whenever you configure summary routes in OSPF, a route to null0 are going to be put in to the OSPF routing desk. This allows to avoid routing loops. Any packets destined for the routes that were summarized will have a longer match during the routing desk, as proven underneath…
C 17.0.0.0/eight is directly linked, Loopback17
C 16.0.0.0/eight is specifically connected, Loopback16
C 19.0.0.0/8 is specifically linked, Loopback19
C 18.0.0.0/8 is right connected, Loopback18
O sixteen.0.0.0/6 is actually a summary, 00:01:51, Null0
.. and packets that do not match one of the summarized routes but do match the summary route is going to be dropped.
Avoiding routing loops when accomplishing route redistribution and summarization is vital. OSPF offers us a bit help in that regard in this case, and while you study extra elaborate redistribution scenarios on your own approach to the CCNP and CCIE, you’ll understand that we’ll consider all the help we may get!